1. Field of the Invention
The present invention relates to a poultry egg which has improved flavor (hereinafter referred to as flavor-improved poultry egg), a method for producing the egg, and foods which are manufactured by the use of the flavor-improved poultry egg.
2. Description of the Related Art
Poultry eggs are of high nutritive value. Nonetheless, their prices have remained low for long periods. Therefore, producers of poultry eggs have pursued economization and have continued searching for inexpensive raw materials for manufacturing feed. As a result, the quality and taste of poultry eggs have been degraded. Feeds for poultry for producing eggs are manufactured using corn, milo, soybean meal, rapeseed meal, fish meal, oils and fats, etc. as starting materials. Particularly when hens are raised with feeds manufactured from fish meal or other starting materials originating from fish, there has been a problem that the resulting eggs tend to have a fishy smell or taste. On the other hand, presumably reflecting consumers' keen interest in healthy foods in recent years, special eggs laid by hens raised with feeds enriched with eicosa-pentaenoic acid (EPA), docosa-hexaenoic acid (DHA), vitamins, etc. are on the market. These eggs, however, also are not free from the problem of having a fishy smell. Presently, the fishy smell of poultry eggs have not yet been completely solved.
Accordingly, reduction or elimination of the fishy smell attributed to starting materials of poultry eggs is desired to thereby improve their flavor.
The present inventors conducted careful studies to solve the above problem and found that hens fed with feeds containing specified natural spices lay eggs having a greatly reduced fishy smell which conventional poultry eggs cannot avoid, and that the eggs laid by the hens fed with such feeds have a rich flavor.
Techniques for adding natural spices to feeds for poultry have been disclosed in Japanese Patent Application Laid-Open (kokai) Nos. 5-276878, 6-14723, 7-31382, and 7-79709, for example. In these publications, it is reported that when poultry raised exclusively for the purpose of producing meat (hereinafter simply referred to as meat poultry) are fed a feed containing natural spices, the resulting meat has a reduced fat content and a less greasy taste, a reduced meaty smell which improves its flavor, and a longer shelf life.
However, the techniques disclosed in those publications are exclusively directed to alteration of the properties of chicken meat by feeding natural spices to hens; the issue of whether or not feeding of natural spices affects the flavor of poultry eggs is not investigated. In particular, Japanese Patent Application Laid-Open (kokai) No. 6-14723 discloses a method for raising meat poultry by feeding them feed containing garlic, ginger, oregano, and cinnamon. However, it has been found that eggs laid by poultry hens fed with feed containing garlic have a poor flavor.
Japanese Patent Application Laid-Open (kokai) No. 6-253749 discloses a method for imparting flavor to poultry eggs by feeding poultry hens with an oily flavor essence dissolved in an organic solvent, and U.S. Pat. No. 4,880,639 discloses a method for imparting flavor to poultry eggs by feeding hens with essential oils of natural spices. However, incorporation of oily flavor essences or essential oils into feeds is disadvantageous in that the flavor is not satisfactorily transferred to poultry eggs, and in addition, the flavor is reduced during storage.